1. Field of the Invention
The present invention relates generally to a power supply apparatus of a portable terminal, and in particular, to an apparatus and method for enabling a power supply for charging a battery in a portable terminal regardless of the charge capacity of a charge cable of an external power supply.
2. Description of the Related Art
Recently, the use of portable terminals is rapidly increasing due to their portability. Thus, service providers (terminal manufacturers) are competitively developing portable terminals with more convenient functions in order to attract more users.
For example, portable terminals provide various functions such as a phone book, a game, a scheduler, a Short Message Service (SMS), a Multimedia Message Service (MMS), an Internet service, an Electronic (E)-mail service, a wake-up call, a Motion Picture Expert Group (MPEG) Audio Layer-3 (MP3) player, and a digital camera.
The portable terminal uses a rechargeable battery in order to provide the advantage of mobility. However, the rechargeable battery has a limited capacity to be charged, and the lifetime of the rechargeable battery decreases with an increase in the use time of the portable terminal. Therefore, when a user of the portable terminal is out or is in long-term travel, the user always has to check the charged state of the rechargeable battery and has to charge the rechargeable battery by an external power supply.
In general, a separate charger, such as a travel charger (TC) or a travel adapter (TA), is used to charge the rechargeable battery by an external power supply.
The charger converts available power, such as power from home-based electrical outlets in the range of 110-220 VAC, or power supplied from a computer, into DC power necessary to charge the portable terminal, and provides the DC power to the portable terminal. The portable terminal charges the battery by the DC power, and operates by the power supplied from the charged battery.
In general, the portable terminal controls the external power supply of a charge Integrated Circuit (IC) by detecting the voltage and current of charging power provided to the battery. Herein, the voltage and current of charging power provided to the battery is the output voltage and output current of the charge IC.
Specifically, when the output voltage of charging power provided to the battery is higher than a predetermined threshold value (for example, 4.2 volt), the portable terminal interrupts the charging power supply to the battery to avoid damaging the charging electronics or the battery.
Also, when the output current of charging power provided to the battery is larger than a predetermined threshold value (for example, 1,000 mA), the portable terminal interrupts the charging power supply to the battery to avoid damaging the charging electronics or the battery.
Accordingly, the portable terminal controls an operation of the charge IC so that the output voltage/current value satisfies the predetermined threshold value.
However, a charge capacity, which means the charge capacity of a charge cable supportable by the portable terminal to provide appropriate or maximum allowable values of voltage and current to charge a device, is set in the portable terminal.
Accordingly, the portable terminal cannot charge the battery when the charge capacity of a charge cable connected to the portable terminal does not correspond to the charge capacity of the portable terminal.
Charge cables supporting various charge capacities are popularized, and a user may have a plurality of charge cables. However, the user can use only the charge cable suitable for a charge capacity set in a portable terminal.
What is therefore required is an apparatus and method for charging a battery in a portable terminal by using charge cables of various capacities.